Globally planarized backend compatible thin film resistor contact/interconnect process

ABSTRACT

A method of forming a thin film resistor contact incorporates an etch-stop material to protect the underlying thin film resistor from a subsequent dry etching process to form a contact opening to the thin film resistor. More specifically, the method includes forming a thin film resistor, forming a first dielectric layer over the thin film resistor, forming a first opening through the first dielectric layer to expose an underlying portion of the thin film resistor, forming an etch-stop within the first opening of the first dielectric layer, forming a second dielectric layer over the etch-stop and the first dielectric layer, forming a second opening through the second dielectric layer to expose the underlying portion of the etch-stop, and forming a metal plug within the second contact opening, wherein the metal plug is in electrical contact with the thin film resistor by way of the etch-stop. Alternatively, in the case of an insulating etch-stop, the second opening through the dielectric layer is through the etch-stop, and forming a metal plug within the second contact opening, wherein the metal plug is in direct electrical contact with the thin film resistor.

FIELD OF THE INVENTION

[0001] This invention relates generally to semiconductor processing, andin particular, to a method of forming a thin film resistor contact.

BACKGROUND OF THE INVENTION

[0002] Thin film resistors are employed in many integrated circuits.Thin film resistors are used in integrated circuits to implement thedesired functionality of the circuit, including biasing of activedevices, serving as voltage dividers, assisting in impedance matching,etc. They are typically formed by deposition of a resistive material ona dielectric layer, and subsequently patterned to a desired size andshape. Often, a thin film resistor is subjected to a heat treatmentprocess (i.e. annealing) to improve its stability and to bring theresistance to a desired value.

[0003] Generally, after all the thin film resistors and other componentsof an integrated circuit are formed, a dielectric layer is deposited toinsulate the resistors and other components from the interconnectwiring. This dielectric layer may be subjected to planarization bychemical-mechanical polishing (CMP) if reduced topography is desiredbefore forming the interconnect wiring. Once the dielectric layer isformed, contacts are made through the layer to make electricalconnections to thin film resistors and other components of theintegrated circuit.

[0004] To minimize any perturbation to the thin film resistors, thesecontacts need to be etched with a process that is highly selective tothe thin film resistor material. Under this requirement, an optimal wetetch process is more readily achievable than a dry etch process andhence preferred. Once the contact openings are made, a metal plugprocess could be used to establish the electrical contact between thethin film resistor and the subsequent interconnect wiring. The metalplug process could be done with deposition of a barrier metal stackfollowed by tungsten, aluminum, and/or copper deposition. In aplanarized backend process where the dielectric above the thin film ispolished to achieve flatness, the preferred method for the metal plugprocess further involves polishing or etch-back of the metal-plugmaterial following its deposition.

[0005] A problem with forming contacts to thin film resistors arisesfrom the fact that the dielectric above the thin film resistors has athickness variation stemming from natural process and process equipmentvariations. If this dielectric is polished, as described above, thisthickness variation is further exacerbated due to the additionalvariation produced by the polish process. Thus, the thin film resistorsacross a wafer or from wafer-to-wafer can be at different depths belowthe top surface of the dielectric layer.

[0006] Because of the different depths of the thin film resistors, theetching of the contact openings has to be conducted in a manner thatguarantees contact opening to the deepest thin film resistor and/orcomponent. As a consequence, the contact openings for shallower thinfilm resistors are overetched. As such, controlled dry etching may bemore difficult to achieve since degradation and/or punch-through of theshallower thin film resistors is highly probable. In the case of wetetching, all thin film contacts are wider due to the isotropic nature ofwet etching. Moreover, the shallower thin film resistor contacts wouldbe further enlarged because of overetching. When metal plugs are usedfollowing the formation of wet-etched contacts, the wide contactopenings lead to incomplete fill. Furthermore, when tungsten is used asthe plug material, poor plug adhesion due to stress and excessiveremoval of the plug due to tungsten polish could result.

[0007] To circumvent the above problem, the dielectric below the thinfilm resistors could be planarized by chemical-mechanical polishingprior to depositing and patterning the thin film resistors.Consequently, topography created by other components of an integratedcircuit are globally planarized. As the addition of thin film resistorstypically adds little topography, this method obviates the need forplanarization of the dielectric deposited above thin film resistors. Butwhile it reduces the problem of dielectric non-uniformity above the thinfim resistors, the increase in dielectric non-uniformity below the thinfilm resistors makes it difficult to employ laser-trimming of individualresistors when high precision resistance values are required. This isbecause the dielectric thickness below the thin film resistors modulatesthe laser irradiation requirements for trimming.

[0008] Thus, there is a need for a method of forming a thin filmresistor contact which eliminates or reduces the drawbacks associatedwith the prior art method of forming thin film resistor contacts. Such amethod and resulting contact is disclosed herein in accordance with theinvention.

SUMMARY OF THE INVENTION

[0009] An aspect of the invention relates to a new and improved methodof forming a thin film resistor contact. With this new and improvedmethod, the above issues associated with dry or wet etching of thecontact openings to thin film are eliminated. Also, with this new andimproved method, the underlying thin film resistors are protected fromthe customary etching process used to make the contact openings. Insummary, the new and improved method of forming a thin film resistorcontact incorporates an etch-stop material to protect the underlyingthin film resistor from a subsequent process of dry etching the contactopening to the thin film resistor. The dry etching of the contactopenings allows more control over the size of the openings, which thenmakes metal plug processes more manufacturable and reliable.

[0010] More specifically, the method of forming a thin film resistorcontact of the invention comprises the steps of forming a thin filmresistor, forming a first dielectric layer over the thin film resistor,forming a first opening through the first dielectric layer to expose anunderlying portion of the thin film resistor, forming an electricallyconductive etch-stop within the first opening of the first dielectriclayer, forming a second dielectric layer over the etch-stop and thefirst dielectric layer, forming a second opening through the seconddielectric layer to expose the underlying portion of the etch-stop, andforming a metal plug within the second contact opening, wherein themetal plug is in electrical contact with the thin film resistor by wayof the etch-stop.

[0011] Another method of forming a thin film resistor contact of theinvention comprises the steps of forming a thin film resistor, forming afirst dielectric layer over the thin film resistor, forming a firstopening through the first dielectric layer to expose an underlyingportion of the thin film resistor, forming an electrically conductiveetch-stop within the first opening of the first dielectric layer andcontinuously over another region of the first dielectric layer that doesnot overlie the thin film resistor, forming a second dielectric layerover the etch-stop and the first dielectric layer, forming a secondopening through the second dielectric layer to expose the underlyingregion of the etch-stop that is not situated over the thin filmresistor, and forming a metal plug within the second contact opening,wherein the metal plug is in electrical contact with the thin filmresistor by way of the etch-stop.

[0012] In the exemplary implementation of the above methods of forming athin film resistor contact, the electrically conductive etch-stop can becomprised of a combination of titanium and titanium-nitride, ortitanium-tungsten and titanium-tungsten-nitride, or other suitablematerial that is electrically conductive and relatively selective to dryetching processes.

[0013] Yet another alternative method of forming a thin film resistorcontact of the invention comprises the steps of forming a thin filmresistor, forming a first dielectric layer over the thin film resistor,forming a first opening through the first dielectric layer to expose anunderlying portion of the thin film resistor, forming an electricallyinsulating etch-stop within the first opening of the first dielectriclayer, forming a second dielectric layer over the etch-stop and thefirst dielectric layer, forming a second opening through the seconddielectric layer to expose the underlying portion of the etch-stop,removing the etch-stop to expose the underlying thin film resistor, andforming a metal plug within the second contact opening, wherein themetal plug is in direct electrical contact with the thin film resistor.

[0014] Still another alternative method of forming a thin film resistorcontact of the invention comprises forming a thin film resistor; formingan electrically insulating etch-stop layer over the thin film resistor;forming a dielectric layer over the etch-stop layer; forming a firstopening through the dielectric layer to expose a first underlying regionof the etch-stop layer; forming a second opening through the insulatingetch-stop layer to expose a second underlying region of the thin filmresistor; and forming a metal plug within the first and second openings,wherein the metal plug is in direct electrical contact with the thinfilm resistor.

[0015] In the exemplary implementation of the above alternative methodsof forming a thin film resistor contact, the electrically insulatingetch-stop can be comprised of a silicon oxynitride, silicon nitride, orother suitable material that is electrically insulating but isrelatively selective to dry etching processes.

[0016] Other aspects of the invention relate to the resulting thin filmresistor contact made by the method of the invention. Additionally,other aspects, features and techniques of the invention will becomeapparent to one skilled in the relevant art in view of the followingdetailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 illustrates a cross-sectional view of an exemplarysemiconductor device at an initial stage of a method of forming a thinfilm resistor contact in accordance with the invention;

[0018]FIG. 2 illustrates a cross-sectional view of the exemplarysemiconductor device at a subsequent step of the method of forming athin film resistor contact in accordance with the invention;

[0019]FIG. 3 illustrates a cross-sectional view of the exemplarysemiconductor device at a subsequent step of the method of forming athin film resistor contact in accordance with the invention;

[0020]FIG. 4 illustrates a cross-sectional view of the exemplarysemiconductor device at a subsequent step of the method of forming athin film resistor contact in accordance with the invention;

[0021]FIG. 5 illustrates a cross-sectional view of the exemplarysemiconductor device at a subsequent step of the method of forming athin film resistor contact in accordance with the invention;

[0022]FIG. 6 illustrates a cross-sectional view of the exemplarysemiconductor device at a subsequent step of the method of forming athin film resistor contact in accordance with the invention;

[0023]FIG. 7 illustrates a cross-sectional view of the exemplarysemiconductor device at a subsequent step of the method of forming athin film resistor contact in accordance with the invention;

[0024]FIG. 8 illustrates a cross-sectional view of the exemplarysemiconductor device at a subsequent step of the method of forming athin film resistor contact in accordance with the invention;

[0025]FIG. 9 illustrates a cross-sectional view of the exemplarysemiconductor device at a subsequent step of the method of forming athin film resistor contact in accordance with the invention;

[0026]FIG. 10 illustrates a cross-sectional view of the exemplarysemiconductor device at a subsequent step of the method of forming athin film resistor contact in accordance with the invention;

[0027]FIG. 11A illustrates a cross-sectional view of the exemplarysemiconductor device at a subsequent step of the method of forming athin film resistor contact in accordance with the invention;

[0028]FIG. 11B illustrates a cross-sectional view of the exemplarysemiconductor device at a subsequent step of an alternative method offorming a thin film resistor contact in accordance with the invention;

[0029]FIG. 12 illustrates a cross-sectional view of an exemplarysemiconductor device at a step of a first alternative method of forminga thin film resistor contact in accordance with the invention;

[0030]FIG. 13 illustrates a cross-sectional view of an exemplarysemiconductor device at a step of a second alternative method of forminga thin film resistor contact in accordance with the invention;

[0031]FIG. 14 illustrates a cross-sectional view of an exemplarysemiconductor device at a step of a third alternative method of forminga thin film resistor contact in accordance with the invention;

[0032]FIG. 15 illustrates a cross-sectional view of an exemplarysemiconductor device at a subsequent step of a third alternative methodof forming a thin film resistor contact in accordance with theinvention; and

[0033]FIG. 16 illustrates a cross-sectional view of an exemplarysemiconductor device after subsequent steps of a third alternativemethod of forming a thin film resistor contact in accordance with theinvention;

DETAILED DESCRIPTION OF THE INVENTION

[0034]FIG. 1 illustrates a cross-sectional view of an exemplarysemiconductor device 100 at an initial stage of a method of forming athin film resistor contact in accordance with the invention. At thisstep, the semiconductor device 100 comprises a substrate 102 and a firstdielectric layer (e.g. silicon dioxide (SiO₂)) 104 disposed over thesubstrate 102. The semiconductor device 100 at this initial stage is anexample of what a semiconductor device may be comprised of prior to theformation of the thin film resistor and its contact in accordance withthe invention. It shall be understood that the semiconductor device 100at this stage may have a different appearance.

[0035]FIG. 2 illustrates a cross-sectional view of the exemplarysemiconductor device 100 at a subsequent step of the method of forming athin film resistor contact in accordance with the invention. At thissubsequent step, a layer of thin film resistor material 106 is formedover the first dielectric layer 104, and then a mask layer 108 is formedover the thin film resistor material 106. The thin film resistormaterial 106 may be comprised of silicon chromium (SiCr), nickelchromium (NiCr), tantalum nitride (TaN), and/or other suitable resistormaterials.

[0036]FIG. 3 illustrates a cross-sectional view of the exemplarysemiconductor device 100 at another subsequent step of the method offorming a thin film resistor contact in accordance with the invention.At this subsequent step, the mask layer 108 is developed and patternedto form a mask 108′ that defines the underlying thin film resistor.

[0037]FIG. 4 illustrates a cross-sectional view of the exemplarysemiconductor device 100 at another subsequent step of the method offorming a thin film resistor contact in accordance with the invention.At this subsequent step, the thin film resistor material 106 is etchedoff except that portion which underlies the mask 108′. This forms a thinfilm resistor 106′. In this example, only the contact region of the thinfilm resistor 106′ is shown in order to illustrate the method of forminga thin film resistor contact in accordance with the invention. The thinfilm resistor material 106 may be etched using anisotropic or isotropicetching techniques.

[0038]FIG. 5 illustrates a cross-sectional view of the exemplarysemiconductor device 100 at another subsequent step of the method offorming a thin film resistor contact in accordance with the invention.At this subsequent step, the mask 108′ is removed. Then, a seconddielectric layer (e.g. a layer of silicon dioxide (SiO₂)) 110 is formedover the thin film resistor 106′ and over the exposed portion of thefirst dielectric layer 104. And, a mask layer 112 is formed over thesecond dielectric layer 110. In the exemplary implementation of themethod of the invention, the second dielectric layer 110 is deposited toa thickness ranging from about few hundred Angstroms to a few thousandAngstroms. The mask layer 112 may be a photo resist or other materialthat can serve as a mask layer.

[0039]FIG. 6 illustrates a cross-sectional view of the exemplarysemiconductor device 100 at another subsequent step of the method offorming a thin film resistor contact in accordance with the invention.At this subsequent step, the mask layer 112 is developed and patternedto form a mask 112′ having an opening 114 that defines the underlyingcontact opening for the thin film resistor 106′. Then, the seconddielectric layer 110 is etched off at a portion underlying the opening114 of the mask 112′ to form contact opening for the thin film resistor106′. The removal of layer 110 at a portion underlying the opening 114is preferably accomplished by wet-etching, though dry-etching may beavailable to one skilled in the relevant art. The remaining seconddielectric layer 110′ serves to passivate the thin film resistor 106′ atthe non-contacted portion of the resistor 106′.

[0040]FIG. 7 illustrates a cross-sectional view of the exemplarysemiconductor device 100 at another subsequent step of the method offorming a thin film resistor contact in accordance with the invention.At this subsequent step, an etch-stop material layer 116 is formed overthe portion of the thin film resistor 106′ underlying the contactopening and over the remaining second dielectric layer 110′. Then, amask layer 120 is formed over the etch-stop material layer 116. In theexemplary implementation of the method of the invention, the etch-stopmaterial layer 116 may be comprised of an electrical conductor, such astitanium and titanium-nitride (Ti/TiN), and/or a titanium-tungsten (TiW)and titanium-tungsten-nitride (TiWN), or any other electricallyconductive material that is selective to a subsequent dry etchingprocess. Alternatively, the etch-stop material layer may be comprised ofan electrical insulator, such as silicon oxynitride, silicon nitride, orother suitable material that is electrically insulating and relativelyselective to dry etching processes. The mask layer 120 may be a photoresist or other material that can serve as a mask layer.

[0041]FIG. 8 illustrates a cross-sectional view of the exemplarysemiconductor device 100 at another subsequent step of the method offorming a thin film resistor contact in accordance with the invention.At this subsequent step, the mask layer 120 is developed and patternedto form a mask 120′ which defines the underlying etch-stop region of theetch-stop material layer 116. Then, the etch-stop material layer 116 isetched off except that portion underlying the mask 120′. This forms anetch-stop 116′ disposed over the thin film resistor 106′ within thecontact opening of the second dielectric layer 110′ and also above theregion of the second dielectric layer 110′ proximate the contactopening. In the exemplary implementation of the method of the invention,the etching of the etch-stop material layer 116 can be performed byanisotropic or isotropic etching techniques.

[0042]FIG. 9 illustrates a cross-sectional view of the exemplarysemiconductor device 100 at another subsequent step of the method offorming a thin film resistor contact in accordance with the invention.At this subsequent step, the mask 120′ is stripped off. Then, adielectric layer 122 is deposited over the etch-stop 116′ and over theexposed portions of the second dielectric layer 110′. After thedielectric layer 122 has been deposited, it may be polished to achieve adesired planarization for its top surface and a desired thickness. Inthe exemplary implementation of the method of the invention, thedielectric layer 122 may be comprised of deposited silicon dioxide(SiO₂) and the polishing of the dielectric layer 122 may be performed bychemical mechanical polishing (CMP).

[0043]FIG. 10 illustrates a cross-sectional view of the exemplarysemiconductor device 100 at another subsequent step of the method offorming a thin film resistor contact in accordance with the invention.At this subsequent step, a contact opening 124 is formed through thedielectric layer 122 to expose the underlying etch-stop 116′. This stepis performed by forming a mask layer (not shown) over the dielectriclayer 122, developing and patterning the mask layer to form an openingabove the to-be formed contact opening, and then dry etching thedielectric layer 122 through the opening of the mask to form the contactopening 124′. The remaining dielectric layer 122′ serves to insulate theunderlying structures of the semiconductor device 100 from theinterconnect wiring to be formed over the dielectric layer 122′.

[0044]FIG. 11A illustrates a cross-sectional view of the exemplarysemiconductor device 100 at another subsequent step of the method offorming a thin film resistor contact in accordance with the invention.In this case, the etch-stop material 116′ is electrically conductive. Atthis step, a metal plug 126 is formed within the contact opening 124′ ofthe dielectric layer 122′. In the exemplary implementation of the methodof the invention, the metal plug 126 is formed by sequentiallydepositing a barrier layer (Ti/TiN) and tungsten (W) to fill the contactopening 124′. Then, the tungsten material is etched or polished back toremove the tungsten (W) off the top surface of the dielectric layer122′. The tungsten plug 126 makes electrical contact to the thin filmresistor 106′ by way of the electrically conductive etch-stop 116′.

[0045]FIG. 11B illustrates a cross-sectional view of an exemplarysemiconductor device 100′ at another step (subsequent to the deviceshown in FIG. 10) of a first alternative method of forming a thin filmresistor contact in accordance with the invention. In this case, theetch-stop material 116″ is electrically insulating. At this step, thecontact opening 124′ is partially formed by etching of the dielectriclayer 122′ using a process that is selective to the etch-stop material116″. Subsequently, the portion of the etch-stop material 116″ thatunderlies the contact opening 124′ is removed using a process that isselective to the thin film resistor 106′. This process could result inan etch-stop spacer 116″ being formed around the perimeter of thecontact opening.

[0046]FIG. 12 illustrates a cross-sectional view of the exemplarysemiconductor device 100′ at another subsequent step of the firstalternative method of forming a thin film resistor contact in accordancewith the invention. At this step, a metal plug 128 is formed within thecontact opening 124′ of the dielectric layer 122′. In the exemplaryimplementation of the method of the invention, the metal plug 128 isformed by sequentially depositing a barrier layer (Ti/TiN) and tungsten(W) to fill the contact opening 124′. Then, the tungsten material isetched or polished back to remove the tungsten (W) off the top surfaceof the dielectric layer 122′. The tungsten plug 128 makes directelectrical contact to the thin film resistor 106′, as opposed to anindirect electrical contact to the thin film resistor 106′ as is thecase when the etch-stop is electrically conductive.

[0047]FIG. 13 illustrates a cross-sectional view of an exemplarysemiconductor device 100″ at a step of a second alternative method offorming a thin film resistor contact in accordance with the invention.In this second alternative method, the electrically conductive etch-stop116″ was formed not only over the thin film resistor 106′, but alsocontinuously over a region that does not overlie the thin film resistor106′. In this scenario, the electrical conductive etch-stop may alsoserve as a local interconnect to other nearby circuit components,subject to design considerations. Also in this second alternativemethod, the metal plug 126″ was formed over the region of the etch-stop116″ that does not overlie the thin-film resistor 106′. Since in thiscase the etch-stop 116″ is electrically conductive, the metal plug 126″makes electrical contact to the thin film resistor 106′ by way of theetch-stop 116″.

[0048]FIG. 14 illustrates a cross-sectional view of an exemplarysemiconductor device 100′″ at a step of a third alternative method offorming a thin film resistor contact in accordance with the invention.In this third alternative method, an electrically insulating etch-stop116′″ is formed over the thin film resistor 106′, instead of the seconddielectric layer 110 as described in the previous methods of forming thethin film resistor contact.

[0049]FIG. 15 illustrates a cross-sectional view of an exemplarysemiconductor device 100′″ at a subsequent step of the third alternativemethod of forming a thin film resistor contact in accordance with theinvention. In this subsequent step, the dielectric layer 122′″ isdeposited over the etch-stop layer 116′″.

[0050]FIG. 16 illustrates a cross-sectional view of an exemplarysemiconductor device 100′″ after subsequent steps of the thirdalternative method of forming a thin film resistor contact in accordancewith the invention. In this case, a contact opening 124″ is formedthrough the dielectric layer 122′″ to expose the underlying etch-stop116′″ using an etching process that is selective to the etch-stop 116′″.Then, the contact opening 124″ is extended through the etch-stop 116′″to expose the underlying thin film resistor 106′ using an etchingprocess that is selective to the thin film resistor 106′. Once thecontact opening 124″ is formed, a metal plug 128′ is formed within thecontact opening 124″.

[0051] An advantage of the described methods of forming a thin filmresistor contact of the invention is that the etch-stop allows theresistor contact opening to be formed by the same dry etching techniquesthat are used to open up the standard contacts to other components of anintegrated circuit. This is because the etch stop protects theunderlying thin film resistor from erosion which may otherwise occurfrom the dry etching if the etch-stop were not present. Since dryetching is typically anisotropic, the dry etching of the contact openingallows the opening 124′ to be more uniform throughout the wafer and fromwafer-to-wafer. The more controllable contact opening is particularlyuseful when tungsten (W) plugs are used, as it avoids a number ofproblems associated with overetched contact openings, such as incompletefills, excessive removal of the plug due to dishing from the polish, andthe peeling of the plugs due to high tensile stress of tungsten.

[0052] In the foregoing specification, the invention has been describedwith reference to specific embodiments thereof. It will, however, beevident that various modifications and changes may be made theretowithout departing from the broader spirit and scope of the invention.The specification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense.

It is claimed:
 1. A method of forming a thin film resistor contact,comprising: forming a thin film resistor; forming a first dielectriclayer over said thin film resistor; forming a first opening through saidfirst dielectric layer to expose a first underlying portion of said thinfilm resistor; forming an electrically conductive etch-stop within saidfirst opening of said first dielectric layer; forming a seconddielectric layer over said etch-stop and said first dielectric layer;forming a second opening through said second dielectric layer to exposea second underlying portion of said etch-stop; and forming a metal plugwithin said second contact opening, wherein said metal plug is inelectrical contact with said thin film resistor by way of saidetch-stop.
 2. The method of claim 1, wherein said first and secondopenings vertically overlap.
 3. The method of claim 1, wherein saidfirst and second openings do not vertically overlap.
 4. The method ofclaim 1, wherein said thin film resistor comprises silicon chromium(SiCr).
 5. The method of claim 1, wherein said thin film resistorcomprises nickel chromium (NiCr).
 6. The method of claim 1, wherein saidthin film resistor comprises tantalum nitride (TaN).
 7. The method ofclaim 1, wherein said etch-stop comprises titanium (Ti) andtitanium-nitride (TiN).
 8. The method of claim 1, wherein said etch-stopcomprises titanium-tungsten (TiW) and titanium-tungsten-nitride (TiWN).9. The method of claim 1, wherein forming said second opening throughsaid second dielectric layer comprises dry etching said seconddielectric layer to form said second opening.
 10. The method of claim 1,wherein said metal plug comprises titanium and titanium nitride.
 11. Themethod of claim 1, wherein said metal plug comprises tungsten.
 12. Athin film resistor contact, comprising: a thin film resistor; a firstdielectric layer with a first opening overlying a first portion of saidthin film resistor; an etch-stop situated within said first opening ofsaid first dielectric layer and in electrical contact with said thinfilm resistor; a second dielectric layer with a second opening overlyinga second portion of said etch-stop; and a metal plug formed within saidsecond opening and in electrical contact with said thin film resistor byway of said etch-stop.
 13. The thin film resistor contact of claim 12,wherein said first and second openings vertically overlap.
 14. The thinfilm resistor contact of claim 12, wherein said first and secondopenings do not vertically overlap.
 15. The thin film resistor contactof claim 12 wherein said thin film resistor comprises silicon chromium(SiCr).
 16. The thin film resistor contact of claim 12 wherein said thinfilm resistor comprises nickel chromium (NiCr).
 17. The thin filmresistor contact of claim 12 wherein said thin film resistor comprisestantalum nitride (TaN).
 18. The thin film resistor contact of claim 12wherein said etch-stop comprises a composition of titanium (Ti) andtitanium-nitride (TiN).
 19. The thin film resistor contact of claim 12wherein said etch-stop comprises a composition of titanium-tungsten(TiW) and titanium-tungsten-nitride (TiWN).
 20. The thin film resistorcontact of claim 12 wherein said metal plug comprises titanium andtitanium-nitride.
 21. The thin film resistor contact of claim 12 whereinsaid metal plug comprises tungsten.
 22. A method of forming a thin filmresistor contact, comprising: forming a thin film resistor; forming afirst dielectric layer over said thin film resistor; forming a firstopening through said first dielectric layer to expose a first underlyingportion of said thin film resistor; forming an electrically insulatingetch-stop within said first opening of said first dielectric layer;forming a second dielectric layer over said etch-stop and said firstdielectric layer; forming a second opening through said seconddielectric layer to expose a second underlying portion of saidetch-stop; removing said etch-stop underlying said second opening; andforming a metal plug within said second contact opening, wherein saidmetal plug is in direct electrical contact with said thin film resistor.23. The method of claim 22, wherein said thin film resistor comprisessilicon chromium (SiCr).
 24. The method of claim 22, wherein said thinfilm resistor comprises nickel chromium (NiCr).
 25. The method of claim22, wherein said thin film resistor comprises tantalum nitride (TaN).26. The method of claim 22, wherein said etch-stop comprises siliconoxynitride.
 27. The method of claim 22, wherein said etch-stop comprisessilicon nitride.
 28. The method of claim 22, wherein forming said secondopening through said second dielectric layer comprises dry etching saidsecond dielectric layer to form said second opening.
 29. The method ofclaim 22 wherein said metal plug comprises titanium and titaniumnitride.
 30. The method of claim 22, wherein said metal plugadditionally comprises tungsten.
 31. A thin film contact, comprising: athin film resistor; a first dielectric layer with a first openingoverlying a first portion of said thin film resistor; an etch stopspacer dispose over said thin film resistor around a perimeter region ofsaid first opening; a second dielectric layer with a second openingoverlying a center region of said first opening; and a metal plugsituated within said center region of said first opening and said secondopening, wherein said metal plug is in electrical contact with said thinfilm resistor.
 32. The thin film resistor contact of claim 31 whereinsaid thin film resistor comprises silicon chromium (SiCr).
 33. The thinfilm resistor contact of claim 31 wherein said thin film resistorcomprises nickel chromium (NiCr).
 34. The thin film resistor contact ofclaim 31 wherein said thin film resistor comprises tantalum nitride(TaN).
 35. The method of claim 31, wherein said etch-stop comprisessilicon oxynitride.
 36. The method of claim 31, wherein said etch-stopcomprises silicon nitride.
 37. The method of claim 31 wherein said metalplug comprises titanium and titanium nitride.
 38. The method of claim31, wherein said metal plug additionally comprises tungsten.
 39. Amethod of forming a thin film contact, comprising: forming a thin filmresistor; forming an insulating etch stop layer over said thin filmresistor; forming a dielectric layer over said etch stop layer; forminga first opening through said dielectric layer to expose a firstunderlying region of said etch stop layer; forming a second openingthrough said etch stop layer to expose a second underlying region ofsaid thin film resistor; and forming a metal plug within said first andsecond opening, wherein said metal plug is in electrical contact withsaid thin film resistor.
 40. The method of claim 39, wherein formingsaid first opening is performed by using an etching process that isselective to said etch stop layer.
 41. The method of claim 39, whereinforming said second opening is performed using an etching process thatis selective to said thin film resistor.
 42. A thin film resistorcontact, comprising: a thin film resistor; an insulating etch stop layerhaving a first opening overlying a region of said thin film resistor; adielectric layer having a second opening overlying said first opening; ametal plug situated within said first and second openings, wherein saidmetal plug is in electrical contact with said thin film resistor.